Cyclic variable speed drive

ABSTRACT

A variable speed drive employing two crank and slider mechanisms so that the speed change created by each of the slider crank mechanisms is multiplied by the speed change created by the other slider crank mechanism. The drive permits variable output speeds from a constant input speed.

United States Patent 1 Johnson [451 July 17,1973

[ CYCLIC VARIABLE SPEED DRIVE [75] Inventor: Ray Clifford Johnson,Holden, Mass.

[73] Assignee: Harris-Intertype Corporation,

Cleveland, Ohio [22] Filed: Aug. 9, 1971 [21] Appl. No.: 170,183

[52] US. Cl 83/313, 83/324, 74/69 [51] Int. Cl 823d 25/02 [58] Field ofSearch 83/313, 324, 284;

[5 6] References Cited UNITED STATES PATENTS 3,659,398 5/1972 Holt83/313 3,613,471 10/1971 Shields 83/324 X 3,286,536 I [/1966 Hallmann74/69 X 2,957,450 10/1960 Phillips, Jr. 74/69 X Primary Examiner-AndrewR. Juhasz Assistant ExaminerW. D. Bray Attorney-Arthur H. Seidel, EdwardC. Gouda and Joel S. Goldhammer [57] ABSTRACT A variable speed driveemploying two crank and slider mechanisms so that the speed changecreated by each of the slider crank mechanisms is multiplied by thespeed change created by the other slider crank mechanism. The drivepermits variable output speeds from a constant input speedv 10 Claims, 4Drawing Figures PAIENIEH JUL I 7 I973 SHEET 1 [IF 4 w M V w RAY CLIFFORDJOHNSON A 77 0 671? VJ:

PATENTED 3.745.865

RAY CLIFFORD JOHNSON ATTOIPA/EYQ PATENIED 3.745.865

' saw a or 4 l/Vlf/VTVP. RAY CLIFFORD JOHNSON ATTOFA/FY PATENIED JUL 1 7I913 SHEET t 0F 4 M M W OFFSET (INCHES) //VI /VTO RAY CLIFFORD JOHNSONAT'IOIQIVEVI.

CYCLIC VARIABLE SPEED DRIVE This invention relates to a cyclic variablespeed drive and more particularly to a cyclic variable speed drive ofthe type employing slider crank mechanisms. The device disclosed can beused on machines where it is desired to have a relatively simple meansfor midifying machine output speed when the input speed is constant. Aparticular application for this variable speed drive is in industrieswhere it is necessary to treat moving webs of material periodically.

A particular need is present in the paper and paperboard industry wherewebs of papers and paperboard are moved at relatively high speeds pasttreatment points. The treatment points may comprise cutting, marking,stamping, punching or the like. The speed of the moving web may bechanged to suit conditions. Accordingly, it is necessary to have asuitable means for modifying the speed of the web treating device sothat it can compensate to change the period for treatment of the web andcause the web contact tool to engage the web while moving at the samespeed as the web.

Mechanisms for so controlling web treating devices of the type describedherein are known in the prior art. For example, such devices are seen inUS. Pat. No. 2,262,913. However, the mechanisms exemplified by the priorart tend to be bulky and heavy resulting in relatively high stressesduring acceleration and deceleration at high speed. Thus, speeds must berestricted to certain operational limits to avoid damage to thecomponents. This invention is distinguishable from and has distinctadvantages over prior art mechanisms including lower dynamic loadforces, thereby minimizing wear and metal fatigue. The critical dynamicforces on the rollers and components associated therewith in thisinvention are only about two-thirds the corresponding forces in themechanism shown in FIG. 7 of said patent.

Generally, my invention relates to a variable speed drive for convertinga constant input motion of constant speed into an output motion ofvariable cyclic speed. The input motion is utilized to drive a slidercrank mechanism which may have its center of rotation varied in order tovary the period for treating the web. The slider crank mechanism isconnected by way of a second slider crank mechanism to a driven outputshaft. The output shaft has a speed which varies cyclically inaccordance with the positioning of the first slider crank mechanism andthe constant input speed. The output shaft is connected to a tool whichis used to treat the moving web.

A specific use for this invention is in a cut off mechanism of apaperboard corrugator wherein webs of paperboard moving at speeds up toabout 800 fpm or more must be cut into sheets having legnths from about22 inches up to about 240 inches. When the sheet length to be cut ischanged, it is desirable to effect the change without slowing down theweb since that can cause excessive waste. Even a loss of l feet ofpaperboard at every changeover results in an ultimate yearly loss ofthousands of dollars. Hence, one feature of this invention is theability to quickly change over from one length of cut to another so asto reduce the waste occasioned by the changeover.

Accordingly, it is an object of this invention to pro vide a novel andimproved variable speed drive.

It is another object of this invention to provide a vari able speeddrive comprised of a minimum of parts.

It is still another object of this: invention to provide a variablespeed drive whose output speed can be altered in a short period of timewhile the machine runs at maximum speed.

It is still another object of this invention to provide a variable speeddrive having low stresses and long life.

Other objects and advantages of the subject invention will be apparentfrom a detailed description thereof which follows wherein FIG. 1 is aschematic respective view showing the various components of the variablespeed drive. I

FIG. 2 is a sectional view taken through a housing supporting thevariable speed drive.

FIG. 3 is a section view taken along the line 33 in FIG. 1.

FIG. 4 is a graph of sheet length versus offset.

In FIG. 1 the variable speed drive 10 in a cutoff machine comprises aninput drive shaft 12 which may run at constant speed. Thus, it may bedriven from any suitable power source such as a synchronous motor 13 orthe like which also drives the web to be cut. The input motion of thedrive shaft 12 is ultimately transmitted to output driven shaft 14 whichis substantially parallel to the input drive shaft 12 but spacedtherefrom.

A drive pinion 16 which is fixed to input drive shaft 12 meshes with aspur gear 18. The spur gear functions as the input driving member of thevariable speed mechanism. To this extent, it is a relatively large gearhaving some of the characteristics of a flywheel promoting therebysmoother running of the machine. A boss 20 is mounted on one of thefaces of the spur gear 18 in spaced relation from its axis of rotation.The boss 20 supports a coupling member such as a stud 22 which rotatablysupports a roller 24. Roller 24 drives rotating arm 26.

The rotating arm 26 includes an elongated portion 28 with an elongatedradially directed slot 29 therein. Slot 29 has a length suitable for thesheet length range of the cutoff. The rotating arm 26 also includes anoutwardly directed porti0n 30. Portion 30 does not extend out as far asthe elongated portion 28. However, it is preferred that portions 28 and30 be diametrically opposed with respect to each other.

The highest torque is at the input side of the mechanism. Hence, roller24 will have a relatively large diameter compared with roller 36.Portion. 28 of rotating arm 26 is tapered to reduce dynamic loads andinertial forces in the mechanism. Hence, the reinforcement rib 27 hasless mass at the outer free end of portion 28 which is where the bendingmoments and stresses are lowest in arm 26.

The rotating arm 26 is supported intermediate its ends for rotation byintegral shaft 32 which may be mounted in a suitable journal block 34.Outwardly extending portion 30 of arm 26 supports a coupling member suchas stud 35 which has a roller 36 at its free end. Roller 36 is receivedin an elongated radially disposed slot 38 in output crank rotor 40. Theoutput crank rotor 40 is fixed to aforementioned output shaft 14.

Portion 30 of arm 26 has a pocket 33 located between stud 35 and shaft32. As illustrated in FIG. 3, pocket 33 is of substantial length anddepth as compared with the length and thickness of portion 30. Pocket 33decreases the twist in portion 30 of arm 26. Thus, pocket 33, by tendingto concentrate stresses on the side edges of roller 36, shifts the shearcenter of portion 30 of arm 26 to a position outside the shear plane ofarm 26 to a position adjacent the plane of rotor 40. This reduction intwist of arm 26 alleviates contact stresses between roller 36 and slot38.

Roller 36 is preferably smaller than roller 24. When roller 24 is 5inches in diameter, roller 36 may be 4 inches in diameter. Roller 36 ispreferably crowned at its periphery to localize contact stresses in thecentral region of slot 38 in rotor 40 and the central plane of saidroller 36. A suitable crown radius for roller 36 when it has a 4 inchdiameter would be approximately 30 inches.

Generally speaking, roller 24 and rotating arm 26 may be characterizedas a first crank and slider mechanism. Roller 36 and crank rotor 40 maybe characterized as a second crank and slider mechanism.

The output shaft 14 drives a first output spur gear 42 which meshes witha second output spur gear 44. Each of the gears has shafts 46 and 48extending therefrom on which are supported their respective tools. Inthe instance of FIG. I, the tools 50 are shown to be cutting blades.However, it is apparent that they could be printing dies, punches or thelike.

As is apparent, the input motion from drive shaft 12 is transmitted byway of pinion 16 and spur gear 18 to the first slider crank mechanism.That mechanism is connected to the second slider crank mechanism whichin turn drives output shaft 14. The velocity of the output shaft 14 withrespect to its angular position depends upon the relative position ofthe longitudinal axis of shaft 32 with respect to the axis of outputshaft 14. The relative position of these two shafts is controlled byproviding means for moving the aforementioned journal block 34. To thisextent, suitable rails 49 or other constraining means are provided. Thejournal block 34 may be provided with overhanging members 52 so that itis constrained for movement along the rails. A threaded shaft 54 isutilized for effecting displacement of the journal block and shaft 32relative to the axis of output shaft 14.

In FIG. 2, the variable speed mechanism is shown supported in a housing60. The housing may be mounted adjacent to a running web of material sothat the tools 50 will be disposed transversely of it.

The principal supporting structure for the variable speed drivecomprises a bearing collar 62 which is supported on the front wall 64 ofthe housing. Main drive spur gear 18 is supported by suitable bearings65 on the outer wall of the bearing collar 62.

Output shaft 14 is supported concentrically within the bearing collar 62while crank rotor 40 is fixed thereto by an elongated sleeve 66. Thus,the output shaft 14, crank rotor 40 and the main drive spur gear 18 areall mounted for rotation about a common axis.

Rotating arm 26 is fixed to journal block 34 by shaft 32. The journalblock is mounted for movement along rails 49 within the housing.Threaded shaft 54 is rotated by way of a suitable motor connected togear 68 disposed outside the housing. Thus, rotation ,of gear 68 movesshaft 32 and arm 26 relative to the aforementioned axis of rotor 40. Themotor connected to gear 68 should be a reversible motor and may be astepper pulse motor 67 whereby a predetermined number of pulses willaccurately move journal block 34 a predetermined distance.

Spur gear 42 is supported on output shaft 14 which is supported near thespur gear by suitable bearings 69.

Spur gear 42 drives spur gear 44 which is supported by bearings 70.

Each of the spur gears 42 and 44 supports driven shafts 46 and 48 onwhich the tool for treating the web of moving material can be mounted.At their opposite ends, each of the shafts 46 and 48 support spur gears72 and 74 which are supported by hearings in a housing 76. Thus, thereis positive drive between the upper and lower shafts 46 and 48 and thetools supported thereby.

It should be appreciated that the subject drive is comprised of aminimum number of moving parts each of which is relatively lightweightand of simple construction. When shafts 32 and 14 are coaxial, thecyclic drive is in its zero position and the velocities of shafts 46 and48 are constant. In a typical machine such as that represented by thegraph in FIG. 4, the zero position corresponds to a sheet length of 34inches. As shaft 32 moves to a position wherein roller 24 approaches theouter end of portion 28 in FIG. 1, sheets smaller than 34 inches inlength will be cut. Block 34 will engage limit stops which establish theallowable limits for the position of rotating arm 26. The distance oftravel for shaft 32 from its position for processing minimum sheetlengths of 22 inches to its position for processing maximum sheetlengths of 240 inches is relatively short, such as 7% inches.

In FIG. 4, there is illustrated a graph of sheet length in inches versusoffset in inches. The word offset refers to the distance between theaxes of shafts l4 and 32. The graph of FIG. 4 is based on the formula:

wherein e is the offset in inches, R is the distance in inches betweenthe longitudinal axes of shaft 32 and roller 36, and SL designates thesheet length in inches which corresponds to the period of the toolconnected to shaft 14. In said formula, the numeral 34 represents thecircumference of the tool path in inches. When the tools 50 are cuttingblades for cutting a web into sheet lengths, the aforementioned periodof the tools determines the cut sheet length. Hence, 34 in said formulawould represent the length of the sheet in I inches which is cut whenthe mechanism is in its zero position of uniform motion and thevelocities of shafts 46 and 48 are constant. The circumference of thepath of the tool 50 is then equal to the length of the sheet cutoff.

The distance between the longitudinal axes of shaft 32 and roller 36equals th distance between the longitudinal axes of shaft 14 and roller24. The graph illustrated in FIG. 4 is based on R being 10 inches.

One of the most important advantages of this invention is that any sheetlength from the minimum size to the maximum size range of the machinemay be cut while operating at high web speeds without excessive stressto the components.

While the invention has been described with reference to cutting paperwebs which may be advanced at various speeds, it is apparent that thesubject invention has many other uses. Exemplary of such uses in thefact that the tool carried by the variable speed drive may be used forstamping, cutting, punching, or printing of moving webs. Theabove-described mechanism causes the tools 50 to cyclically increase anddecrease speed so that the tools are at web speed when the tools engagethee web.

Accordingly, while the invention has been described with reference toone particular embodiment thereof, it is apparent that many other formsand embodiments will be obvious to those skilled in the art in view ofthe foregoing description. Thus, the scope of the invention should notbe limited thereby, but rather only by the scope of the claims appendedthereto.

1 claim:

1. A cyclic variable speed drive comprising a first axis of rotation, adrive input member supported for rotation about said first axis ofrotation, first means defining another axis of rotation, an arm, said ambeing mounted on said first means for rotation about said other axis,said arm including a first portion having an elongated radial slot and asecond portion directed in substantially the opposite direction fromsaid slot, driven output means, said driven output means axis beingcoaxial with said first axis of rotation, a rotor, said rotor beingconnected to said driven output means to drive it about said first axisof rotation, said rotor including an elongated radially directed slot,first and second elongated coupling members disposed in substantiallyparallel relation to said first axis of rotation, said first couplingmember having one end fixed to said drive input member and having aroller on its other end rotatably received in said first arm slot forrotating said arm, said second elongated coupling member having one endfixed to said arm second portion and having its other end rotatablyreceived in said rotor slot for rotating said rotor, and means formoving the arm in a direction perpendicular to said axes for changingthe distance between said first and second axes in opposite directionsfrom a zero position to cyclically vary the speed of said driven outputmeans relative to the speed of saId drive input member.

2. A variable speed drive in accordance with claim 1 wherein said rotorand arm are tapered so as to have less mass at one free end thereof, andsaid second coupling member having a crown roller disposed in the sloton said rotor.

3. A variable speed drive in accordance with claim 1 wherein the secondcoupling member terminates in a roller disposed in the rotor slot, theroller on said first coupling member having a larger diameter than theroller on said second coupling member.

4. A variable speed drive in accordance with claim 1 including first andsecond cutting blades mounted on shafts, gear means coupling saidshafts, the shaft for said first blade being connected to said drivenoutput means.

5. A variable speed drive in accordance with claim 1 wherein said armsecond portion has a pocket so that the shear center of the arm isoutside a vertical plane containing the arm.

6. A cyclic variable speed drive comprising an output shaft rotatableabout its longitudinal axis to drive a tool, a rotor fixed to saidoutput shaft so that rotation of said rotor causes said output shaft torotate, means for cyclically driving said rotor, said means including asupport shaft rotatable about an axis parallel to said output shaft, anelongated arm fixedly connected intermediate its ends on said supportshaft for rotation about the axis of said shaft, one end portion of saidarm being coupled to said rotor by a coupling member constrained forradial movement on said arm, the other end portion of said am beingtapered toward the free end thereof and having a radially disposed slottherein, a roller means constrained for movement in said slot, saiddriving means being operative to cause said roller to rotate said armabout said support shaft, motor means for moving the axis of rotation ofsaid support shaft from a zero position where it is coaxial with thelongitudinal axis of said output shaft to maximum and minimum offsetpositions on opposite sides of the zero position, and the distancebetween the maximum offset position and the minimum offset positionbeing less than 8 inches.

7. A variable speed device as defined in claim 6 wherein said am has apocket on said one end portion between said coupling member and saidshaft, said pocket being on a side face of said arm remote from saidrotor and having a depth greater than one-half the thickness of said oneend portion.

8. A variable speed device in accordance with claim 6 wherein a crownedroller is supported by said coupling member, said rotor having a slotreceiving said crowned roller and being rotatably driven thereby.

9. A variable speed drive in accordance with claim 6 wherein the offsetbetween the axes of said shafts is defined by:

web.

1. A cyclic variable speed drive comprising a first axis of rotation, adrive input member supported for rotation about said first axis ofrotation, first means defining another axis of rotation, an arm, saidarm being mounted on said first means for rotation about said otheraxis, said arm including a first portion having an elongated radial slotand a second portion directed in substantially the opposite directionfrom said slot, driven output means, said driven output means axis beingcoaxial with said first axis of rotation, a rotor, said rotor beingconnected to said driven output means to drive it about said first axisof rotation, said rotor including an elongated radially directed slot,first and second elongated coupling members disposed in substantiallyparallel relation to said first axis of rotation, said first couplingmember having one end fixed to said drive input member and having aroller on its other end rotatably received in said firsT arm slot forrotating said arm, said second elongated coupling member having one endfixed to said arm second portion and having its other end rotatablyreceived in said rotor slot for rotating said rotor, and means formoving the arm in a direction perpendicular to said axes for changingthe distance between said first and second axes in opposite directionsfrom a zero position to cyclically vary the speed of said driven outputmeans relative to the speed of saId drive input member.
 2. A variablespeed drive in accordance with claim 1 wherein said rotor and arm aretapered so as to have less mass at one free end thereof, and said secondcoupling member having a crown roller disposed in the slot on saidrotor.
 3. A variable speed drive in accordance with claim 1 wherein thesecond coupling member terminates in a roller disposed in the rotorslot, the roller on said first coupling member having a larger diameterthan the roller on said second coupling member.
 4. A variable speeddrive in accordance with claim 1 including first and second cuttingblades mounted on shafts, gear means coupling said shafts, the shaft forsaid first blade being connected to said driven output means.
 5. Avariable speed drive in accordance with claim 1 wherein said arm secondportion has a pocket so that the shear center of the arm is outside avertical plane containing the arm.
 6. A cyclic variable speed drivecomprising an output shaft rotatable about its longitudinal axis todrive a tool, a rotor fixed to said output shaft so that rotation ofsaid rotor causes said output shaft to rotate, means for cyclicallydriving said rotor, said means including a support shaft rotatable aboutan axis parallel to said output shaft, an elongated arm fixedlyconnected intermediate its ends on said support shaft for rotation aboutthe axis of said shaft, one end portion of said arm being coupled tosaid rotor by a coupling member constrained for radial movement on saidarm, the other end portion of said arm being tapered toward the free endthereof and having a radially disposed slot therein, a roller meansconstrained for movement in said slot, said driving means beingoperative to cause said roller to rotate said arm about said supportshaft, motor means for moving the axis of rotation of said support shaftfrom a zero position where it is coaxial with the longitudinal axis ofsaid output shaft to maximum and minimum offset positions on oppositesides of the zero position, and the distance between the maximum offsetposition and the minimum offset position being less than 8 inches.
 7. Avariable speed device as defined in claim 6 wherein said arm has apocket on said one end portion between said coupling member and saidshaft, said pocket being on a side face of said arm remote from saidrotor and having a depth greater than one-half the thickness of said oneend portion.
 8. A variable speed device in accordance with claim 6wherein a crowned roller is supported by said coupling member, saidrotor having a slot receiving said crowned roller and being rotatablydriven thereby.
 9. A variable speed drive in accordance with claim 6wherein the offset between the axes of said shafts is defined by: eR(1 - Square Root K/SL) wherein e is the offset in inches, R is thedistance in inches between the longitudinal axes of the support shaftand the crowned roller, SL designates sheet length which corresponds tothe tool period and K is the circumference of the tool path in inches.10. A variable speed device in accordance with claim 9 wherein said toolis a cutting blade and the tool period corresponds to the sheet lengthscut from a moving web.